The present invention relates to the field of pulley devices for tensioning idlers or runner rollers designed to interact with a chain or a belt, for example a distribution belt of an internal combustion engine of a vehicle.
Such rollers are usually used to keep a constant tension on the belt or chain in a determined range or to locally modify the path taken by the latter. These are then called respectively tensioning idlers or runner rollers. In runner rollers, the pulley is mounted so as to rotate on a screw or a spindle by means of a rolling bearing, the roller then being attached directly or indirectly to the engine block or to an element of a tensioning idler device, for example an articulated arm or an eccentric.
To fasten the roller to its support, a spacer is usually used in association with the said screw or spindle. During this assembly, it is desirable that the spindle or the screw is axially secured to the other elements forming the roller and comprising the pulley. This provides an undismantleable assembly that is easy to handle and carry and can be easily mounted.
For this purpose, document DE-B4-100 03 208 discloses a pulley for a belt tensioning idler comprising a rolling bearing, a spacer for the mounting of the rolling bearing and a fastening screw immobilized axially relative to the spacer. The axial retention relative to the fastening screw and to the spacer is carried out by means of a continuous ring mounted by clamping onto a threaded portion of the fastening screw.
A major disadvantage of this solution is that it does not allow a particularly secure and effective retention of the fastening screw relative to the spacer. There is therefore a risk of accidental dismantling of the elements forming the pulley device.
Also known, through document WO-A1-2007/036407, is a pulley device for a tensioning idler comprising a pulley, a rolling bearing, a flange capable of pressing against an element external to the device, a fastening screw immobilized axially relative to the flange, and a friction ring provided between the flange and the screw.
The relative fastening of the flange and the fastening screw by friction contact does not make it possible to ensure in a certain manner over time the securing of these two elements.